The present invention relates to a control valve for controlling the flow of a fluid. The invention is particularly applicable to solenoid-actuated control valves of the diaphragm type, and is therefore described below with respect to such valves, but it will be appreciated that the invention could advantageously be used in other types of control valves as well.
Many types of control valves are known including a valve member (e.g., a diaghragm in a diaphragm-valve) which is movable to open and closed positions with respect to a passageway between an inlet port and an outlet port of the valve. One type includes a plunger reciprocatable within a chamber to an extended position causing the valve member (diaphragm) to close the passageway, or to a retracted position permitting the valve member to open the passageway. Such valves, however, are not entirely satisfactory for a number of applications. For example, in applications requiring relatively high-frequency operation (e.g., in the order of 15-80 actuations per second), such high-speed operation is usually not attainable with the known diaphragm valves of this type because of the magnitude of the plunger reciprocatory movement required during each valve operation. Another disadvantage of the known diaphragm valves of this type is that the fluid flow through the valve in its open condition is usually prefixed by the smallest cross-sectional area in the fluid path when the valve member is in its open position, which means that many different valve sizes are required for different applications involving different flow rates, thereby increasing the manufacturing costs and the inventory requirements for such valves.
An object of the present invention is to provide a control valve having advantages in the above respects.
According to a broad aspect of the present invention, there is provided a control valve for controlling the flow of a fluid, comprising a housing having an inlet port, an outlet port, and a passageway therebetween; and a valve assembly disposed within the housing and including a valve member movable to open and closed positions with respect to the passageway. The valve assembly further includes a plunger reciprocatable within the housing to an extended position wherein one end of the plunger engages the diaphragm causing the diaphragm to close the passageway, or to a retracted position permitting the diaphragm to open the passageway. The control valve further includes a coiled spring enclosing the plunger and having one end secured to the plunger, and the opposite end secured to the housing for urging the plunger to one of the positions; and an actuator for actuating the plunger to the other of said positions; and a presettable limit member presettable within the chamber to be engaged by the end of the plunger opposite to that engageable with the valve member to fix the retracted position of the plunger, and thereby to preset the magnitude of reciprocatory movement of the plunger and the cross-sectional area of the passageway when the plunger is in its open position.
As indicated above, the invention is particularly useful with respect to diaphragm-type control valves, wherein the valve member is a diaghragm.
Control valves, particularly of the diaphragm type, constructed in accordance with the above features provide a number of important advantages over the presently known diaphragm-type control valves: One important advantage is that by presetting the limit member, the magnitude of the reciprocatory movement of the plunger can be pre-fixed, e.g., shortened in order to increase the speed of operation of the control valve; thus, diaphragm-type control valves of known construction operating at a maximum speed of 12 operations per second have been modified in accordance with the foregoing features to increase their speed to about 80 operations per second. Another advantage in the foregoing construction is that by presetting the position of the limit member, the position of the plunger in its retracted condition can be preset to fix the cross-sectional area of the passageway between the inlet and outlet ports; thus, control valves may be supplied according to a standard construction and then adjusted, by presetting the limit member, to adapt it to the various applications requiring different flow rates.
Further features and advantages of the invention will be apparent from the description below.